The Screw-Mounted or Press-Fit Type Shelf Support by Hafele is for invisible fastening of shelves with a 19 mm wood thickness or greater in living room, kitchen, bath and bedroom areas. Adjustable without tools by turning the plastic sleeve. Adjust height and level, set the shelf on the shelf supports mounted in the wall and then adjust by turning the plastic sleeves. The Hexagonal end on the shelf support permits installation with 1/4" using a cordless drill or a 6mm open end or box-end wrench. Can be installed directly into masonry walls or woodwork. To make adjustments possible, the insertion hole must be laterally elongated, with a slot drilling machine or a chain mill.